Non-contact Tonometry Versus Pachymetry Corrected Intraocular Pressure: Any Difference? A Case for Pachymetry during Glaucoma Screening

Objective: This study sets out to determine if there is any statistical difference in the results of measuring intraocular pressure (IOP) uncorrected for Central Corneal Thickness with Air Puff Tonometry and corrected with pachymetry for clients undergoing screening for glaucoma at the department of Ophthalmology, University of Port Harcourt Teaching Hospital (UPTH), Nigeria.

Methods: One hundred and thirty-two (132) adults were screened for glaucoma during the 2019 World Glaucoma week in UPTH Port Harcourt, they had their IOPs measured with Air Puff (Non-contact) Tonometer (Pulsair intelliPuff Tonometer, Keeler), after which they underwent pachymetry (Sonomed Escalon PacScan Plus) to determine corneal thickness after which the corrected IOP was determined by using a correction factor for adjusting IOP based on corneal thickness [1]. The results were analyzed using SPSS version 20 to determine statistical differences.

Results: There was a statistically significant difference between intraocular pressure (IOP) measurements when corrected with pachymetry than when it is uncorrected. In our study the mean uncorrected IOP RE and LE was 14.53 mmHg and14.75 mmHg respectively while Corrected IOP RE and LE was 16.37 mmHg and 16.72 mmHg respectively.

Conclusion: Intra ocular pressure measurement adjusted with pachymetry for corneal thickness may be a better option for tonometry and we propose this be considered during intra ocular pressure measurement.